The sluggish start to the day, the struggle to concentrate on everyday tasks and the lethargy that comes with just a few hours sleep, these are the symptoms that will be familiar to anyone who suffers with insomnia.
But according to research, not all sleepless nights are the same. Brain scans have revealed evidence for distinct forms of insomnia, each with an associated pattern of neural wiring.
And while the clinical distinction may mean little to those whose days are blighted by sleep deprivation, the discovery does raise the prospect of tailored interventions for people with different kinds of insomnia, which could lead to better treatments.
Researchers at the Netherlands Institute for Neuroscience in Amsterdam analysed MRI scans from more than 200 insomniacs and dozens of sound sleepers and spotted structural changes that distinguished sleepers from the sleepless and five separate forms of insomnia.
“If these subtypes differ in their biological mechanism, then patients in each subtype might benefit from different focused treatments,” said Tom Bresser, a neuroscientist and first author on the study.
Insomnia is broadly defined as poor sleep, generally due to difficulties falling or staying asleep, which negatively affects daytime functioning. About a third of adults in western countries have sleep problems at least once a week, with up to 10% qualifying for a formal insomnia diagnosis.
Chronic insomnia is diagnosed if someone suffers sleep problems on at least three nights a week for three months or more. The condition is nearly twice as common in women than men.
Doctors recommend going to bed and waking at the same time each day, exercising daily, relaxing for at least an hour before bed, and making sure the bedroom is dark and quiet. Avoiding big meals late at night and not smoking or drinking alcohol or caffeine at least six hours before bedtime also helps.
In the latest work, published in Biological Psychiatry and led by Prof Eus van Someren, the team looked at MRI brain scans from 204 people with insomnia who had been grouped according to the subtypes. The scans revealed brain structure differences between the subtypes, providing further evidence that they are rooted in biology.
The researchers think personality and mood traits can be used to categorise insomnia because their influence may be similar during sleep and waking hours. For example, if people tend to be badly affected by stress during day-to-day life, stress may also be more likely to interfere with their sleep.
It means, for example, that meditation, an effective relaxation technique, may help with subtypes characterised by high energy levels before bed. Patients with some forms of insomnia are more likely than others to develop depression, so clinicians could offer early preventive therapy to these individuals.
Prof Tsuyoshi Kitajima, who studies sleep at the Fujita Health University in Japan, said it was surprising that insomnia subtypes derived from questionnaires had such biological differences in the brain scans. “I think this study provides significant evidence for the validity of the authors’ subtyping,” he added.
Dieter Riemann, a professor of clinical psychophysiology at the University of Freiburg in Germany, called the work “highly interesting” and said it may encourage clinicians to take insomnia more seriously. “Many of them see insomnia as a minor complaint or a symptom, but if it has some neurobiological underpinning then that would mean we have to take insomnia more seriously than we did before,” he said.
